Refractory-article and method of making it.



S. P. HALL.

REFRACTORY ARTICLE AND METHOD OF MAKING IT.

APPLIOATION FILED D110. 26, 1908.

1,030,999. Patented July 2, 1912.

"11H WI 40 conventional form of electric furnace, inditill NiagaraFalls,

SAMUEL F. HALL, OF NIAGARA FALLs,

NEW YORK, ASSIGNOR TO NORTON COMPANY,

OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

REFRACTORY'ARTICLE temperatures.

Attem ts have heretofore been made to cast mo ten alumina or otherrefractory oxids or combinations of thesein molds, but such efforts havenot prov-ed successful partly by reason of. the diflieulties encoun'tered in tapping the molten product from the furnace or otherwisetransferring it to the mold. rrccording to the present inventionarticles consisting of such refractory oxids are produced by heating theoxid, for example alumina, to 'a state of quiet fusion in an electricmersing in the fused mass a mold or form,

' usually of carbon or graphite, withdrawing the mold together with theadhering or contained oxid, and separating or detaching the solidifiedoxid from the mold. By proceeding in this manner I have foundit practiscable-to produce a variety of articles, such as rods, tubes, vessels orthe like, without flaws, cracks or objectionable irregularities, and, inthe with any desired thickness of wall.

For a full understanding of my invention -reference is made to theaccompanying drawing, wherein Figure 1 1s a vertical sectional view of areferred manner of forming the eating a 3, are side elevations atarticles; 4 igs. 2,

I right angles to each other of a moldfor producing small rods ofrefractory oxids; F-ig.4 is a perspective view of a sect onal tube mold;Fig. 5 is a transverse section of the 7 same, showing the tube in place,and Fig. 6

cling pipe is a vertical sectional View of a crucible mold.

' tric furnace having metal walls 1 adaptedto be cooled by a sprayofwater from an encir- 2, and a refractory hearth 3.

Specification of Letters Patent.

furnace, then dipping or 1m opposite channeled sections 910 assembledcase of tubes or hollow articles,

In the drawings, I have illustrated an elec-' AND METHOD OF MAKING IT.

' Patented July 2, i912.

Application filed December 26, 1908. Serial No. 469,325.

'la'rity depending into a mass of molten refractory oxid 5, for examplealumina. The furnacewalls are protected by a solid layer 6 of thematerial constitutingthe charge. I have indicated in this figure themanner of manipulating the mold 7. v Y

The mold may be of carbon or graphite, the latter being preferred byreason of its high-heat conductivity and the ease with which it may bemachined; or other mas terials, as refractory metals or metallic c0mpounds may be used. Iron molds may successfully be employed. Certainforms of mold are indicated in Figs.2-6, inclusive. Thus in Figs. 2, 3,I have shown a plate 7 having. transverse perforations 8 adapted for theproduction of small rods of alumina. These perforations become filledwith molten alumina or other molten oxid when the plate is dipped orimmersed in a bath of the same. This oxid is almost instantly solidifiedbv the transfer of heat to the mold, and shrinks slightly in solidifyingso that the rods are readily removed.

Fig. 4 represents a tube mold comprising in any usual or desired manner,as by the use of dowels, tenons or the like.- The assembled moldprovides a cylindrical smoothwalled opening 11 traversing it from end toend. \Vhen this mold is dipped for a part or all of its length in thebath of molten oxid, its surfaces-become coated with a solidified layer,the portion of the layer coating the interior walls constituting asmooth-Walled and readily removable tube of refractory oXid as indicatedat 12 in Fig. 5. The thickness of this layer depends upon the quantityof heat transferred to the mold, and therefore upon the heat capacity ofthe'mold and the duration of its immersion; it follows that for a givenmold the thickness of the internal wallofthe mold without using a core,liability to fracture on'cooling is avoided, and the normal shrinkage ofthe oxid serves to loosen or detach the article.

Obviously, the

' Fig. 6 illustrates a moldconsisting of a plate or bar 13 having one ormore CI'11C1bl-.

shaped cavlties 14.,the crucible'being formed,

in this manner.

heated before dipping, as thls results in a I nous materiahwhlchconsists in melting an without the use of a core, of the solidifiedlayer of refractory oxid as before. Obviously a wide variety of formsmay bemade The molds are'preferably smoother and more uniform deposit.

I have observed that articles produced as above described may exhibitcontrasting colors or shades, being dark colored or black on the sidewhich was in contactwith the mold, and-in case of rods, pins, or thelike,

throughout their mass; while tubes, cruci-' bles and other hollowarticles are usually much lighter in color at and near their innerfaces. This color variation is presumably due to the state or degree ofoxidation of the material of the article, including the impuritiesusually contained therein. In the dark colored portions such impuritiesas iron, silicon, and titanium, and'even a ortion of the aluminum,-mayexist in the orm of carbidsor other products of reduction,

whereas in the lighter portions of, the article these metals existwholly or largely as oxidized'compounds. I have further found thatarelatively light color may be im arted to the whole mass of the articleby firing the same-under oxidizing conditions.

- from themold;

I claim 1.- The method of making'articles of realuminous materialproduced in a'carbon or fractory oxids, which consists in melting saidoxidsin an electric furnace, di ping a mold int-0' themolten mass, withrawing the mold together with. the adhering layer of solidified oxid,and separating the article 2,'The method of making articles ofrefractory oxids, which consists in melting va said oxide in; anelectric furnace, dipping into the molten mass it mold ha'vlngan 111-ternal surface corresponding to the-exters the mold.

In testimony whereof, I afiix my signa nal surface (if ;the desiredarticle, withdrawing the mold together with the adherring layer ofsolidified oxid, and separating the article from the mold, A

3. The method of making articles of alumialuminous material in anelectric furnace,

dipping a mold into the molten mass, withnous material, which consistsin melting an aluminous material in an electric furnace.

dipping into themoltenmass a mold havin an lnternal surface of graphite"correspon 'ing to the external surface of the desired article,Withdrawing the mold together with the adhering layer of solidifiedoxid, and separating the article from the mold.

5. The method of making articles of refractory oxide, which consists inmelting said oxids in an electric furnace, dipping a carbon or graphitemold into, the molten mass, Withdrawing the mold :together with theadhering layer of solidified oxid, sepa- I rating the article from themold, and finally heating the article under oxidizing conditions.

6. An article consisting essentially of an graphite mold andcharacterized by a dis:

article at and near its surface of contactwith ture in presence of twowitnesses.

, SAMUEL HALL.

Witnesses:

CARL E. TUC ER, KATHRYN CALDWELL.

